The nematode, Caenorhabditis elegans, provides an excellent model system in which to study chromatin-mediated mechanisms of gene regulation during gametogenesis and early embryogenesis. The powerful genetic approaches available in C. elegans allow the isolation and manipulation of mutants for factors that participate in sex-specific chromatin organization in the germline. The focus of this proposal is to determine the functional consequences and underlying mechanisms of the observed sex-specific chromatin assembly and subsequent epigenetic maintenance in the resulting embryo. The underlying epigenetic mechanisms that establish and maintain genetic imprinting are likely to be conserved, and the proposed studies will provide insights into these processes in other organisms, including mammals. Specifically, the hypothesis that imprinting of the X chromosome by passage through the male germline in C. elegans provides a chromatin-based silencing mechanism that functions before the establishment of somatic dosage compensation will be tested. The specific aims of this proposal are therefore: 1) to determine the functional consequences of sex-specific germline chromatin assembly in embryonic development and 2) to uncover genetic factors that are mechanistically involved in establishing and regulating this process.